How to generate Optional

I want to create JCodeModel for the below method:

private static Optional<Class<?>> getTypeOfId(String fieldName) {
        switch (fieldName.toLowerCase()) {
            case "IDFORCLASSX":
            {
                return Optional.of(X.class);
            }
            default:
            {
                return Optional.empty();
            }
        }
    }

I am presently using below code for creating the return type of the class.

AbstractJClass optionalOfClassType = codeModel.ref(Optional.class)
 .narrow(codeModel.ref(Class.class)
 .narrow(codeModel.ref("?")));

But the above code gives a high priority FindBug error PRMC_POSSIBLY_REDUNDANT_METHOD_CALLS.

Can anyone help me to optimize the above line of code?